Unless otherwise indicated herein, the description provided in this this section is not itself prior art to the claims and is not admitted to be prior art by inclusion in this section.
A typical cellular wireless network includes a number of base stations each radiating to define a respective coverage area in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices (whether or not technically “user” operated), can operate. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs served by the base station.
Further, a cellular wireless network may operate in accordance with a particular air interface protocol or “radio access technology,” with communications from a base station to UEs defining a downlink or forward link and communications from UEs to the base station defining an uplink or reverse link. Examples of existing air interface protocols include, without limitation, Orthogonal Frequency Division Multiple Access (OFDMA (e.g., Long Term Evolution (LTE)), Code Division Multiple Access (CDMA) (e.g., 1×RTT and 1×EV-DO), Wireless Interoperability for Microwave Access (WiMAX), and Global System for Mobile Communications (GSM), among others. Each protocol may define its own procedures for registration of mobile terminals, initiation of communications, handover between coverage areas, and other functions related to air interface communication.
In accordance with the air interface protocol, each coverage area may operate on one or more carrier frequencies or range of carrier frequencies. Further, each coverage area may define a number of channels or specific resources for carrying signals and information between the base station and mobile terminals. For instance, certain resources on the downlink may be reserved to carry a pilot or reference signal that UEs may detect as an indication of coverage and may measure to evaluate coverage quality. Further, certain resources on the uplink may be reserved to carry access requests from UEs seeking to connect with the base station. And certain resources on the downlink may be reserved to carry control messaging such as paging messages and access response messages from the base station. In addition, certain resources on the uplink and downlink may be set aside to define shared channels for carrying bearer traffic and other communications, with the base station scheduling use of those shared channel resources on an as-needed basis.
When a UE enters into coverage of a base station, the UE may engage in a process to establish a radio-link-layer connection with the base station. This process may take various forms, depending on the air interface protocol. By way of example, once the UE detects coverage of the base station, the UE may send to the base station an access request message such as a randomly selected access code, and the base station may then send an access response message that provides an allocation of uplink shared channel resources on which the UE can request a radio-link-layer connection. The UE may then transmit on the allocated uplink resources a request to establish a radio-link-layer connection and may include in that request an identification of the UE. And in response, the base station may grant the UE's request to establish the radio-link-layer connection and may store a record indicating the existence and identity of the radio-link-layer connection.
Further, as part of this process or subsequently (e.g., via the radio-link-layer connection), the UE may register or attach with the base station so as to trigger setup of various records and connections in the network for the UE. By way of example, the UE may send to the base station an attach request, which the base station may forward to a control entity such as a mobility management entity or the like. After the network engages in a process of authenticating the UE, the control entity may then engage in signaling to set up one or more bearer tunnels (“bearers”) for the UE between the base station and a gateway system that provides connectivity with a transport network such as the Internet, the gateway system may assign an Internet Protocol address to the UE, and the base station may maintain a context record associating each such bearer with the UE's radio-link-layer connection. In practice, for instance, the control entity may work to set up various types of bearers for the UE based on a service profile record for the UE, with each bearer possibly having a different respective quality of service. For example, the control entity may set up a default best-efforts bearer for general data communication, and the control entity may set up a higher quality bearer for carrying certain types of session setup signaling or the like. Other examples are possible as well.
Once the UE has a radio-link-layer connection with the base station and has one or more established bearers, the base station may then schedule air interface communications to and from the UE. For instance, when the gateway system receives data destined to the UE, the gateway system may forward the data to the base station, the base station may then select particular downlink shared channel resources on which to transmit the data to the UE, and the base station may (i) transmit on a downlink control channel to the UE a scheduling directive designating the selected resources and (ii) transmit the data to the UE on the designated resources. Similarly, when the UE has data to transmit onto the Internet, the UE may transmit a scheduling request on an uplink control channel to the base station, and the base station may then select particular uplink shared channel resources on which the UE can transmit the data and may transmit to the UE on a downlink control channel a scheduling directive designating the selected resources. In turn, the UE may then transmit the data on the designated resources to the base station, and the base station may forward the data via a bearer established for the UE to the gateway system for transmission onto the Internet.
In addition, in this or other arrangements, when no data has flowed to or from a UE for a threshold period of time, the network may be arranged to automatically release the UE's established radio-link-layer connection and perhaps one or more bearers for the UE between the base station and the gateway system, while maintaining at least some network records and/or connections for the UE. At that point, the UE may then be considered to be in an “idle” or “dormant” state, in which the UE does not have a radio-link-layer connection with the base station. In that state, if the gateway system has data to transmit to the UE or if the UE has data to transmit to the gateway system, the UE may need to engage in an access and connection process similar to or the same as that described above, to acquire a radio-link-layer connection over which the data can flow, transitioning the UE back to a “connected” or “active” state. In practice, for instance, if the gateway system has data to transmit to an idle UE, the gateway system may signal to the control entity, and the control entity may responsively cause the base station to page the UE, in response to which the UE may engage in the access and connection process to transition to a connected state. Likewise, if an idle UE itself has data to transmit, the UE may responsively engage in the access and connection process to transition to a connected state. And the base station may then schedule the communication in the manner noted above.